Optical information recording medium

Abstract

In a control method of an optical disk unit, it is judged by performing a tentative tracking operation of an optical pickup in a constant region of an optical disk whether a tracking position of the optical pickup is located in a land or groove portion. After a correct tracking control condition is judged, an access operation according to command information is executed. The optical disk unit has a two-divisional light receiving element for receiving diffracted light caused by a pregroove and a prepit of the optical disk, and a differentiator for generating a difference signal between signals of this light receiving element. The optical disk unit further has an adder for generating a sum signal of the signals of the light receiving element, and a tracking signal selector for selecting the difference or sum signal when the tracking operation is performed in a pregroove or prepit region, respectively. An optical information recording medium and a method for recording and regenerating information by using this optical information recording medium are also shown.

What is claimed is: 
     
       1. An optical information recording medium having a groove and a prepit series for tracking and constructed such that a central line of the prepit series is approximately shifted from a central line of the groove by P/4 on one of left-hand and right-hand sides when P is set to a distance between grooves; and no groove is formed in a preformat region constructed by the prepit series, wherein a phase of depth Dp of a prepit and a phase depth Dg of a groove are approximately equal to each other and are ranged from 0.1×(2n+1)λ to 0.2×(2n+1)λ where n is set to 0, 1, 2, - - - , and λ is set to a wavelength of a laser converging beam for recording and regenerating information.   
     
     
       2. An optical information recording medium as claimed in claim 1, wherein a preformat mark constructed by a mirror mark portion having no groove and no prepit is formed within the preformat region constructed by the prepit series. 
     
     
       3. An optical information recording medium as claimed in claim 1, wherein a preformat mark having the same pattern and constructed by the prepit series on each of central lines of a groove and a land is formed within the preformat region constructed by the prepit series. 
     
     
       4. An optical information recording medium having a groove and a prepit series for tracking and constructed such that a central line of the prepit series is approximately shifted from a central line of the groove by P/4 on one of left-hand and right-hand sides when P is set to a distance between grooves; and no groove is formed in a preformat region constructed by the prepit series, wherein the relation between a half-value groove width Wp with respect to a prepit depth and a diameter BD of a laser converging beam for recording and regenerating information is set to 0.19≦Wp/BD≦0.44 where BD is set to 1/e 2  value.   
     
     
       5. An optical information recording medium as claimed in claim 4, wherein a preformat mark constructed by a mirror mark portion having no groove and no prepit is formed within the preformat region constructed by the prepit series. 
     
     
       6. An optical information recording medium as claimed in claim 4, wherein a preformat mark having the same pattern and constructed by the prepit series on each of central lines of a groove and a land is formed within the preformat region constructed by the prepit series. 
     
     
       7. An optical information recording medium having a groove and a prepit series for tracking and constructed such that a central line of the prepit series is approximately shifted from a central line of the groove by P/4 on one of left-hand and right-hand sides when P is set to a distance between grooves; and no groove is formed in a preformat region constructed by the prepit series, wherein the relation between a half-value groove width Wg with respect to a groove depth and a diameter BD of a laser converging beam for recording and regenerating information is set to 0.38≦Wg/BD≦0.56 where BD is set to 1/e 2  value.   
     
     
       8. An optical information recording medium as claimed claim in claim 7, wherein a preformat mark constructed by a mirror mark portion having no groove and no prepit is formed within the preformat region constructed by the prepit series. 
     
     
       9. An optical information recording medium as claimed in claim 7, wherein a preformat mark having the same pattern and constructed by the prepit series on each of central lines of a groove and a land is formed within the preformat region constructed by the prepit series.